Mudline casing hanger assembly

Abstract

A mudline casing hanger assembly wherein the collet (10) is retained on the hanger body (12) during running by tensile coupons (26). The lower portion (32) of the coupon is retained in slot (24) with collet slots (22) and hanger flowby slots (48) being aligned.

We claim: 
     
       1. A casing hanger assembly for supporting a casing string within and from a tubular member comprising: a cylindrical hanger body having a downwardly-facing load shoulder at an upper elevation, first attaching means at a lower elevation, means for supporting a casing string from said hanger body, and a reduced diameter portion between said load shoulder and said first attaching means; a diametrically compressible collet surrounding said hanger body at said reduced diameter portion having, an upwardly-facing support shoulder at the upper end adapted to support said load shoulder, outwardly-extending latch means adapted to engage mating grooves in the tubular member, and a second attaching means located on the collet; a plurality of tensile coupons, each comprising a vertically elongated member attached to said first and second attaching means, and having a weakened section between the attached ends, said weakened section being strong enough to pull the collet into and through a riser casing but weak enough to break when the load of the casing string is imposed. 
     
     
       2. A casing hanger assembly as in claim 1: said tensile coupons each being an elongated plate with their minor dimension radial to said collet, whereby said coupon is flexible in the radial direction and stiff in the circumferential direction. 
     
     
       3. A casing hanger assembly as in claim 2: said collet having a plurality of downwardly-opening slots, each of said tension coupons passing through said slots. 
     
     
       4. A casing hanger assembly as in claim 3: wherein said second attaching means holds said tensile coupons against rotation around a horizontal axis, whereby each coupon is maintained vertical even after breaking of the coupon. 
     
     
       5. A casing hanger assembly as in claim 4: said hanger body having an intermediate diameter portion between said reduced diameter portion and said load shoulder, said collet being held below said intermediate portion when said tensile coupons are intact; the distance between said support shoulder in the recessed position and said load shoulder being less than the distance between said weakened section of the coupon and the bottom of said collet, whereby said tension coupon maintains alignment of said collet even after breakage. 
     
     
       6. A casing hanger assembly as in claim 5: wherein said collet has overlapping alternately upwardly- and downwardly-opening slots, whereby said collet compresses without circumferential movement. 
     
     
       7. A casing hanger assembly as in claim 6: said hanger having flowby slots past said load shoulder, the upwardly-opening slots of said collet being aligned with the flowby slots. 
     
     
       8. A casing hanger assembly as in claim 1: the upper end of each tensile coupon and said collet having interengaging load bearing surfaces, and the lower end of each tensile coupon and hanger body having interengaging load bearing surfaces in addition to means for retaining the upper and lower ends of each coupon to said collet and hanger body, respectively. 
     
     
       9. A casing hanger assembly as in claim 4: the upper end of each tensile coupon and said collet having interengaging load bearing surfaces, and the lower end of each tensile coupon and hanger body having interengaging load bearing surfaces in addition to means for retaining the upper and lower ends of each coupon to said collet and hanger body, respectively. 
     
     
       10. A casing hanger assembly as in claim 5: the upper end of each tensile coupon and said collet having interengaging load bearing surfaces, and the lower end of each tensile coupon and hanger body having interengaging load bearing surfaces in addition to means for retaining the upper and lower ends of each coupon to said collet and hanger body, respectively. 
     
     
       11. A casing hanger assembly as in claim 7: the upper end of each tensile coupon and said collet having interengaging load bearing surfaces, and the lower end of each tensile coupon and hanger body having interengaging load bearing surfaces in addition to means for retaining the upper and lower ends of each coupon to said collet and hanger body, respectively.